1. Field of the Invention
The present invention generally relates to an alignment device for a hole saw and method for guiding hole boring tools and more particularly pertains to an alignment device for a hole saw and method used for enlarging existing holes in a work piece, such as a door.
2. Description of the Prior Art
There exist a number of hole saw guides within the prior art. With respect to the invention, such hole saw guides have been employed for the purpose of enlarging existing holes as is the case where small hole exists in a door, for example, where a lock previously existed and a larger hole is required to install a larger lock in the door. In such case, various hole saw guides have been used.
For example, U.S. Pat. No. 5,366,326 to Converse discloses a hole saw guide for alignment of a hole saw used to enlarge an existing hole. The hole saw guide includes a perforated cylindrical plug fitted to an existing hole. The perforation accepts the hole saw pilot drill member permitting free rotation. The perforated cylindrical plug includes a stop which prevents passage of the plug through the existing hole. The problem with this type of device is that the plug is limited to a particular existing hole size and must be friction fit and requires a hammer to install and remove.
U.S. Pat. No. 5,871,310 to Martensen discloses a device for use in combination with a hole saw of the type including a cylindrical hollow body having a circular lower cutting edge, a top mandrel with a shank in engagement with a chuck of a drill and a pilot bit for guiding the hole saw when cutting a new opening in a work piece having a predrilled opening, in which the center of the new opening lies within the predrilled opening. The device includes a dowel plug having a plurality of holes therethrough, wherein a pilot bit of the hole saw can be positioned in a rotatable manner into one of the holes in the dowel plug on center or off center with the predrilled opening in the work piece. The problem with this type of device is that the plug tends move when operating the hole saw thus not providing an off angled opening for the lock to be disposed therein.
U.S. Pat. No. 4,579,486 to Damico discloses a hole saw guide used to position a hole saw while forming a new hole of larger diameter with or without maintaining concentricity with the existing hole. The Damico invention permits enlargement of an existing hole by employing a plurality of screws and locking nuts or sliding arms to engage the existing hole sidewalls and thereby locating a guide hole for the pilot drill of a larger hole saw. The Damico invention means for assuring concentricity of the enlarged hole with respect to the existing hole includes adjustable arms or screws which engage the sidewalls of the existing hole. Since there is no provision for maintaining an isometric relationship of the independently adjustable arms or screws there cannot be an assurance of concentricity without difficult and tedious readjustment.
The background art has made efforts to attempt to form and enlarge holes using various hole enlargement devices. The prior devices while somewhat useful fail to provide an adequate solution and there remains a need to improve the art. The present invention substantially fulfills this need. The present invention achieves its intended purposes, objects, and advantages through a new, useful and unobvious combination of method steps and elements. The prior patents and commercial techniques do not suggest the present invention as disclosed and claimed herein.